There has been proposed several routing strategies such as Ad hoc On-Demand Distance Vector Routing (AODV), Dynamic Source Routing (DSR), Destination-Sequenced Distance-Vector Routing (DSDV) and the like for a wireless ad hoc network. Among them, the AODV protocol is the focus of research and is widely used. In the AODV, routing establishment and routing selection are two critical stages. At the stage of routing establishment, a source node transmits a route request (RREQ) packet to a destination node. The route request packet is a broadcasting packet which will be forwarded by intermediate nodes in a flooding manner. At the stage of routing selection, a route with a minimum hop count will be used as an effective path to the destination node from the source node. This routing method is very helpful to reduce routing control overhead and to improve efficiency. However, at the stage of routing establishment, a node forwards the RREQ packet transmitted by the source node in the flooding manner, which leads to following issues. Firstly, each node would forward the RREQ packet blindly (in the flooding manner), resulting in a large number of redundant information over the network. Secondly, the large number of RREQ packets transmitted by the nodes over the network would increase the probability of collision of the data packets. Thirdly, transmission and reception of the RREQ packets would occupy network resources, and therefore the transmission of the large number of redundant RREQ packets would result in reduction of the network performance.